A wide variety of micro-electromechanical devices (MEMS) are known, including accelerometers, DC relay and RF switches, optical cross connects and optical switches, microlenses, reflectors and beam splitters, filters, oscillators and antenna system components, variable capacitors and inductors, switched banks of filters, resonant comb-drives and resonant beams, and micromirror arrays for direct view and projection displays. There are a wide variety of methods for forming MEMS devices, including a) forming micromechanical structures monolithically on the same substrate as actuation or detection circuitry, b) forming the micromechanical structures on a separate substrate and transferring the formed structures to a circuit substrate, c) forming circuitry on one substrate and forming micromechanical elements on another substrate and bonding the substrates side by side or in a flip-chip type arrangement. Regardless of the actual method used, at some point in the manufacturing process for making MEMS devices, a sacrificial layer is generally removed in order to release the micromechanical structure. The released structure is then able to be actively actuated or moved, such as pivoting or rotation of a micromirror for a projection display or optical switch, or movement during sensing, such as an accelerometer in an automobile airbag system.